1. Field of the Invention
This invention relates to gasoline dispensing nozzles having means for automatically shutting off delivery into a receiving vessel when filled, and for removing displaced vapors from said receiving vessel. The invention is particularly concerned with providing means for shutting off gasoline delivery when liquid gasoline is drawn or displaced from the receiving vessel into the vapor removal means.
2. Description of the Prior Art
Most conventional gasoline dispensing nozzles have automatic shut-off devices incorporated therewith for terminating the flow of gasoline into a receiving vessel when it has been filled. Such devices normally comprise an orifice situated in the nozzle spout and a venturi within the nozzle housing, both of which lead by suitable passageways to the same portion of a chamber divided by a diaphragm. Until the receiving vessel is filled, air is simply drawn through the orifice and aspirated into the gasoline flowing through the venturi. But when the receiving vessel is filled, the orifice becomes flooded with gasoline and air can no longer be aspirated in this manner. Hence, the flow of gasoline through the venturi creates a suction which forces the diaphragm to move a sufficient distance to activate a trigger mechanism, such as that shown in U.S. Pat. No. 2,582,195, for releasing the spring-to-close main valve within the nozzle housing.
In addition to automatic shut-off devices, many gasoline dispensing nozzles are equipped with means to remove vapors generated in the receiving vessel during the filling thereof. Generally, such nozzles are designed to remove vapors by sealing the entrance of the gasoline tank fill pipe from the atmosphere so that vapors may be displaced, or induced under a slight negative pressure of about 1-2 inches of water, through an annular opening surrounding the nozzle spout into a vapor removal line. However, because some modern gasoline tank fill pipes are substantially horizontal near the opening, it is possible to insert the nozzle into the fill pipe such that the nozzle spout is tipped slightly upwardly. Since the sensing orifice is usually located at the end of the nozzle spout, it will thus be held at an elevation slightly higher than the lowest portion of the annular entrance to the vapor removal line. Hence, after rising up the fill pipe, liquid gasoline will be drawn or displaced into the vapor removalline without concomitantly flooding the sensing orifice that activates the automatic shut-off device.
This problem is even more acute when it is necessary to turn the nozzle sideways or even upside down to fill the gasoline tank. In such unnatural positions, the sensing orifice may be an inch higher in elevation than the lowest portion of the annular entrance to the vapor removal line. Hence, again, gasoline would be pumped into the vapor removal line to the vapor recovery facilities without ever triggering the automatic shut-off device.